From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Kirill A. Shutemov" Subject: Re: [PATCH v5 3/5] mm: introduce mmap3 for safely defining new mmap flags Date: Wed, 16 Aug 2017 19:47:17 +0300 Message-ID: <20170816164717.xjbtbdjtwnhvzukg@node.shutemov.name> References: <150286944610.8837.9513410258028246174.stgit@dwillia2-desk3.amr.corp.intel.com> <150286946261.8837.1454297295346610351.stgit@dwillia2-desk3.amr.corp.intel.com> <20170816111541.6c4ulnipt5cxgfsb@node.shutemov.name> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" To: Dan Williams Cc: Jan Kara , Arnd Bergmann , "linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org" , Linux API , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Linux MM , Andy Lutomirski , linux-fsdevel , Andrew Morton List-Id: linux-api@vger.kernel.org On Wed, Aug 16, 2017 at 09:35:11AM -0700, Dan Williams wrote: > On Wed, Aug 16, 2017 at 4:15 AM, Kirill A. Shutemov > wrote: > > On Wed, Aug 16, 2017 at 12:44:22AM -0700, Dan Williams wrote: > >> diff --git a/include/linux/mman.h b/include/linux/mman.h > >> index c8367041fafd..0e1de42c836f 100644 > >> --- a/include/linux/mman.h > >> +++ b/include/linux/mman.h > >> @@ -7,6 +7,40 @@ > >> #include > >> #include > >> > >> +#ifndef MAP_32BIT > >> +#define MAP_32BIT 0 > >> +#endif > >> +#ifndef MAP_HUGE_2MB > >> +#define MAP_HUGE_2MB 0 > >> +#endif > >> +#ifndef MAP_HUGE_1GB > >> +#define MAP_HUGE_1GB 0 > >> +#endif > >> + > >> +/* > >> + * The historical set of flags that all mmap implementations implicitly > >> + * support when file_operations.mmap_supported_mask is zero. > >> + */ > >> +#define LEGACY_MAP_SUPPORTED_MASK (MAP_SHARED \ > >> + | MAP_PRIVATE \ > >> + | MAP_FIXED \ > >> + | MAP_ANONYMOUS \ > >> + | MAP_UNINITIALIZED \ > >> + | MAP_GROWSDOWN \ > >> + | MAP_DENYWRITE \ > >> + | MAP_EXECUTABLE \ > >> + | MAP_LOCKED \ > >> + | MAP_NORESERVE \ > >> + | MAP_POPULATE \ > >> + | MAP_NONBLOCK \ > >> + | MAP_STACK \ > >> + | MAP_HUGETLB \ > >> + | MAP_32BIT \ > >> + | MAP_HUGE_2MB \ > >> + | MAP_HUGE_1GB) > >> + > >> +#define MAP_SUPPORTED_MASK (LEGACY_MAP_SUPPORTED_MASK) > >> + > >> extern int sysctl_overcommit_memory; > >> extern int sysctl_overcommit_ratio; > >> extern unsigned long sysctl_overcommit_kbytes; > > > > Since we looking into mmap(2) ABI, maybe we should consider re-defining > > MAP_DENYWRITE and MAP_EXECUTABLE as 0 in hope that we would be able to > > re-use these bits in the future? These flags are ignored now anyway. > > Yes, we can make these -EOPNOTSUPP in the new syscall. You cannot detect them, if we would redefine them as 0. :) -- Kirill A. Shutemov